The Flora of the PCT: Wildflowers, Trees and Shrubs

RT Hawke, Shaun Hawke and Tom Chester

Fig. 1. Left: the PCT logo on a trail sign on the PCT Section D1 in the San Gabriel Mountains from Interstate 15 to Lone Pine Canyon Road. Right: the PCT tunnel that goes under Highway 14 by Acton, echoing the shape of the PCT logo. Pictures taken by RT Hawke. Click on the pictures to get larger versions.

Trail Sections With Links to the Plant Checklists
Information About The Plant Checklists


The Pacific Crest Trail (PCT) runs from Mexico to Canada, providing a wonderful opportunity for a plant transect the north-south length of the United States. However, an exhaustive plant list is typically impossible to create for any flora, and even more so with a project of this magnitude. In a perfect world, the best scenario would be to botanize the entire trail (~2650 miles) many times in a number of seasons, preferably most in peak bloom, and in multiple years. Such a protocol is almost impossible and would likely take decades to complete. Our default option for methodology means doing a lot of forensic botany, in areas out of our comfort zone of botanical knowledge that contain a number of unknown plants to us. All projects have to start in some manner, however imperfectly. We settled on recording what plants we could, in order to help understand the diversity and distribution of the plants along the trail. Hopefully, other botanists and wildflower enthusiasts will improve upon the list in the future.

My wife and I chose to do an average pace at about one mile per hour, which is too fast to be completely thorough, but slow enough to find the majority of the plants. Tom Chester and other botanists might go at a much slower botanical pace and find nearly everything in a part of a section that could be identified on a given day. Therefore, the level of completeness for trail section plant lists may vary, and will be described in how many times that section of the trail has been surveyed, if it was peak blooming time, and how many botanists were present.

In particular, when the habitat of the trail segment is fairly uniform, and the trail is covered at peak bloom in a good year, and it is an area where we know the plants well, the completeness of a single survey might be fairly high, 80 to 90% of the total number of species one would find by doing many surveys at many times of year in many years by many different people. However, if there is a large range of elevation on a trail segment, such that different parts of the trail bloom at different times, and/or if the trail was not covered at peak bloom, and/or if it wasn't a good rainfall year, the completeness might be less than 50%. An extreme example of the latter is Section A8b, whose first survey was done when most plants were dormant, in a poor rainfall year, finding 70 species. (To do a flora of the entire PCT, one doesn't have the option of covering every section at peak bloom in a good year.) In subsequent surveys at different times of year in two different years, the number of species climbed to 182, then 217, and then 222 in the fourth survey, where each of those surveys concentrated on just a few miles of the eight total miles of this segment.

Since the magnitude of this project is so immense, we invite other botanists to contribute. Tom Chester is the web master of this project, and contributions can be directed to him.

Trail Sections With Links to the Plant Checklists

We have divided the trail into main sections A-Z. This breaks up the trail into sections that mostly correlate to geomorphic provinces with similar vegetation. We have further divided those alphabetical sections into sub-sections. This divides the trail even further into smaller pieces, which range from 2 to 24 miles depending on access, logistics and elevation. I suspect most of the sections will probably range from 10-15 miles. These sections will always start or end near a trail access. Those sections with long mileage and without reasonable access will be again broken into subsections (a,b,c) and will start or end at some random mileage, geographic feature or trail junction. This will at least facilitate a list at both ends (a, and c). The section narratives are sequential from south to north, although there are many parts of the trail that are easier to hike from north to south. Day Hikes of the PCT by Semb (2000), is useful for information on access to the trail, although their trail sections do not correlate to ours.

Mileages are rounded to the nearest half mile, and elevations are given to the nearest 50 feet.

Table 1. Sections of the PCT

Section LetterSection Description
A Southern Peninsular mountain ranges, Hauser Mountain, Laguna Mountains and the San Felipe Hills.
BThe San Ysidro and San Jacinto Mountains.
C San Bernardino Mountains
DThe San Gabriel Mountains
EThe Sierra Pelona Mountains.
FThe Mojave Desert and Southern Sierras.
GThe High Sierras.
HThe Northern Sierras.
IMount Lassen and the Southern Cascades.
JMount Shasta region.
KKlamath range.
LMarble Mountains.
MSiskiyou Mountains
NCascade Ranges of Southern Oregon

Information About The Plant Checklists

Since this project is a work in progress, the plant checklists will vary in their completeness and accuracy, and in how complete the webpage is for each section. An example of a complete webpage, with four different formats for the checklist, is San Gabriel Mountains D7, Islip Saddle to Eagles Roost.

Each checklist is sorted first by category, such as ferns, gymnosperms, dicots and monocots, and then by family and scientific name. The categories, Family and Scientific Name are from the 2012 Second Edition Jepson Manual

The scientific name is linked to the latest online Jepson Manual description for each species, which also gives the months in which each species flowers. That link also gives a map of where the species occurs in California; a plot of elevation vs. latitude for California; and a histogram of the voucher collections by month.

The common name for most species in the checklist is linked to Calphotos to give pictures of most taxa.

Each list is also placed into Calflora which generates an illustrated version of a list with two photos for each plant. A link is given in each checklist to that Calflora version.

Links may be provided to lists of voucher specimens from the nearby area, and to pages with pictures of the plants on a particular section, such as to the San Gabriel Mountain Photo Galleries of Michael Charters.

Not every species can be identified securely in a trip done at just one time of year, and hence it is important to note any qualification on a given determination. On the lists, unidentified plants that are just in a vegetative state, but are most likely to be a good candidate due to voucher specimens from the nearby area are marked with a (v). Other plants we may only be able to get to genus, and that best guess, either genus or specific epithet, will be placed in parentheses.

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Copyright © 2012-2015 by RT Hawke, Shaun Hawke and Tom Chester.
Permission is freely granted to reproduce any or all of this page as long as credit is given to us at this source:
Comments and feedback: Tom Chester
Updated 2 January 2015.